In order to construct the damage constitutive model (DCM) of high-concentration cemented backfill (HCCB) in coal mine, the generalized Hoek-Brown strength criterion was used as the failure criterion. For the difference of theoretical derivation of constitutive relation, a new DCM based on residual strength was proposed. Combined with the conventional triaxial compression test, the correctness and rationality of the DCM were verified. The damage evolution characteristics of HCCB were analyzed, and the physical meaning of model parameters was clarified. The results show that (a) the theoretical curves of stress-strain relation are in good agreement with its experimental curves, which means DCM can simulate the deformation and failure process of HCCB. (b) The damage evolution curve of HCCB is -shaped. To some extent, the confining pressure can inhibit the development of damage. (c) The parameter reflects the position of the peak point of the DCM, and parameter is the slope of the straight line segment in the postpeak strain softening stage, which are, respectively, used to characterize the strength level and brittleness of HCCB. The establishment of DCM of HCCB is helpful to reveal its deformation and failure mechanism and provides theoretical basis for its strength design.

In order to reduce the segregation degree of cemented backfilling slurry in coal mine and enable cemented backfill in coal mine (CBCM) to normally exert its load-bearing capacity, uniaxial compressive strength test, static segregation index test and microscopic properties test were carried out. The effect of suspending agent content (SAC) on the strength, static segregation index and microscopic properties of CBCM was discussed. The relationship between static segregation index and microscopic properties and backfill strength was analyzed. The results show that when SAC increases from 0 to 0.06%, the backfill strength increases first and then decreases, the static segregation index of backfilling slurry decreases by 46.81%, and the Ca(OH)₂ content in backfill decreases by 24.51%. The increase of SAC can improve the strength of CBCM, reduce the segregation degree of backfilling slurry and reduce the hydration products inside the backfill. The backfill strength increases first mainly because SAC reduces the segregation degree of backfilling slurry, and the backfill strength decreases later mainly because SAC inhibits the hydration reaction inside the backfill.

In order to accurately understand the primary rupture law of main roof in long-wall face, the principal bending moment was visualized with the aid of MATLAB software, the rupture direction of each region of the main roof was theoretically analyzed, the rupture sequence of each region of the main roof was explored, and the rupture law of the main roof was verified based on the model experiment. The research results show that: (1) The point where the absolute value of the control bending moment in the long-side region is the largest is the midpoint of the long side. The absolute value of the control bending moment in the length direction of the working face is greater than that in other directions. (2) The point with the maximum control bending moment in the middle region is the midpoint of the middle. The control bending moments in the length direction of the working face are greater than those in other directions. (3) The point where the absolute value of the control bending moment in the short-side region is the largest is the midpoint of the short side. The absolute value of the control bending moment in the propulsion direction of the working face is greater than that in other directions. (4) Under various influencing factors, the absolute value of the control bending moment at the midpoint of the long side is the largest, and the absolute value of the control bending moment at the midpoint of the short side is the smallest. The main roof breaks first from the midpoint of the long side. As the coal mining face advances, the midpoint of the middle and the midpoint of the short side break successively, eventually forming an O-X type rupture morphology. The revelation of the primary rupture law of main roof in long-wall face is conducive to carrying out the support design of the working face, improving the management level of mine pressure, and ensuring the safe production of the coal mining face.

In response to the insufficiency of shear strength and severe segregation of cemented backfilling material in coal mines, a shear strength test, static segregation index test, and homogeneity degree test were carried out, taking slurry concentration (SC) as the main control factor. The effect law of SC on shear strength, the static segregation index, and the homogeneity degree was discussed. The relationship between the static segregation index and homogeneity degree and shear strength was analyzed, and the action mechanism of SC on shear strength was revealed. The research results show that for cemented backfill in coal mines, with a suspending agent content of 0 and a curing age of 28 d, when SC increases from 77% to 80%, shear strength increases by 31.43%, the static segregation index of the backfilling slurry decreases by 40.29%, and the homogeneity degree of the backfill increases by 69.23%. The increase in SC can enhance shear strength, reduce the segregation degree of backfilling slurry, and improve the homogeneity of backfill. The reason for the increase in shear strength lies in the fact that SC reduces the segregation degree of the backfilling slurry. The research in this paper has certain guiding significance for the timely support of the surrounding rock in the working face and the effective control of surface settlement.